MASS ANALYSER

PURPOSE:To enable the simultaneous measurement of a specimen from a plurality of gas chromatograph columns (GC) by one mass spectrometer (MS), by providing a specimen selection unit between the outlet of said column and the ion source of MS. CONSTITUTION:The specimen flowed out from the column of GC 1 is ionized by the ion source of MS and the ion beam of said ion source is passed through a magnetic field and only the ion beam satisfying a specific condition is taken in a collector 7 and the spectrum of the specimen is analyzed and recorded on the basis of the signal MS, a plurality of GCs 1 are provided and a section unit 2 is provided between each GC 1 and the ion source 3. Each unit 2, a provides a gap between the specimen supply pipeline in the side of GC 1 and that in the side of the ion source 3 and He-gas is sprayed to said gap so as to cross the flow of the specimen at right angles. The specimens from a plurality of GCs 1 are introduced into the ion source 3 of MS in good order by the units 2 made synchronous to the scanning of the magnetic field by the signal from CPU and measured values are put in order by CPU 9 to make it possible to process the specimen flowed out from a plurality of GCs by one MS.